Lift truck for hot vessels, particularly for steel-mill converters

ABSTRACT

The lift truck has an undercarriage with driving means for moving the truck along tracks and carrying hydraulic actuators operable to lift the undercarriage at track intersections to change the direction of movement of the truck. Two pairs of piston-cylinder hydraulic actuators are mounted on the undercarriage and each actuator includes a cylinder supported on the undercarriage to extend vertically upwardly therefrom and a piston movable upwardly in the associated cylinder and carrying an enlarged piston head. Pairs of tie rods are supported on each piston head through universal or gimbal type Cardan joints for universal swinging movement, and the lower ends of the tie rods are also provided with the same general type of joints. The tie rods associated with each pair of actuators support a respective stirrup so that, when the pistons are extended, the associated stirrups are lifted. These stirrups engage beneath a reinforcing ring or the like on a hot vessel, such as a steel-mill converter, and are operable to lift the vessel upwardly to engage the vessel in a tilting cradle or support in which the vessel is then locked. The gimbal or Cardan type connections of the tie rods to the piston heads and to the stirrups provide for adjustment of the tie rods and stirrups to the orientation assumed by the converter when the latter is being inserted into a tilting support.

United States Patent [191 Trost [451 Feb. 27, 1973 [75] Inventor:

[73] Assignee: Demay Aktiengesellschaft, Duisburg,

Germany [22] Filed: Jan. 21, 1971 [2]] Appl. No.: 108,468

Werner Trust, Duisburg, Germany [30] Foreign Application Priority Data Feb. 24, 1970 Germany ..P 20 08 396.9

[52 us. Cl ..214 1 1), 266/36 P 51] int. c1 ..B65g 1/00 [58] Field ofSearch...2l4/1 D, l R, 1 Q, 130 R, 313, 214/315; 187/318, 38 CC, 8.59, 8.74, 8.75; 266/35, 36 R, 36 P, 36 H, 39; 105/177 Primary Examiner-Drayton E. Hoffman Assistant Examiner-Frank E. Werner Attorney-John J. McGlew and Alfred E. Page [5 7] ABSTRACT The lift truck has an undercarriage with driving means for moving the truck along tracks and carrying hydraulic actuators operable to lift the undercarriage at track intersections to change the direction of movement of the truck. Two pairs of piston-cylinder hydraulic actuators are mounted on the undercarriage and each actuator includes a cylinder supported on the undercarriage to extend vertically upwardly therefrom and a piston movable upwardly in the associated cylinder and carrying an enlarged piston head. Pairs of tie rods are supported on each piston head through universal or gimbal type Cardan joints for universal swinging movement, and the lower ends of the tie rods are also provided with the same general type of joints. The tie rods associated with each pair of actuators support a respective stirrup so that, when the pistons are extended, the associated stirrups are lifted. These stirrups engage beneath a reinforcing ring or the like on a hot vessel, such as a steel-mill converter, and are operable to lift the vessel upwardly to engage the vessel in a tilting cradle or support in which the vessel is then locked. The gimbal or Cardan type connections of the tie rods to the piston heads and to the stirrups provide for adjustment of the tie rods and stirrups to the orientation assumed by the converter when the latter is being inserted into a tilting support.

10 Claims, 4 Drawing Figures LIFT TRUCK FOR I-IOT VESSELS, PARTICULARLY FOR STEEL-MILL CONVERTERS BACKGROUND OF THE INVENTION The invention is directed to a transportation lift truck for hot vessels, particularly for steel-mill converters, with a hoisting arrangement for a supported vessel and an undercarriage which is movable along tracks by suitable driving means and which can be lifted, together with the vessel, at track intersections by means of several hydraulic actuators carried by the undercarriage, so that the truck may be rotated to assume a different direction of movement along the track.

Various arrangements have been proposed for stabilizing a transportation lift truck in various phases during the lifting of a hot vessel, during the transfer to different tracks at track intersections, and during the take-over or delivery of the vessel to its tilting support or cradle. However, the problem of inserting the vessel properly into the tilting support or cradle, and transferring the vessel to the holding elements provided in the support, remains still unsolved. Consequently, the design of a transportation lift truck is incomplete if it serves only for the mere transportation of the hot vessel or steel-mill converter. The particular difficulties encountered in transfer of the vessel from the lift truck to the tilting support thus represent a critical point in the vessel or converter changing system.

Considered alone, the function of a vessel changing system is to limit the down times in converter blowing stands to a minimum. The necessary measures comprise substantially the periods dismantling the worn vessel, transferring the vessel to the transportation lift truck, transporting the vessel to the clearing station and relining the vessel.

The following measures overlap, in time, with the measures just mentioned. As soon as a converter vessel, with a worn lining, has been removed from its support, a previously relined and heated vessel can be placed in the converter blowing stand. With regard to the measures that are necessary again, there are no difficulties in bringing in the heated vessel, and the heating itself furthermore can take place in the blowing stand. The subsequent transfer of the vessel to the tilting base is the actual subject matter of the present invention.

The necessary starting point is the fact that the vessel must not be damaged during transfer from the lift truck to the tilting base, which would involve major intolerable damage. Because of its thermal conductivity, the vessel has a high elasticity and always varies its dimen' sions at the bearing points during a furnace campaign and after relining. The original conditions of the initial lining, and those of the original construction, respectively, no longer exist after the first relining. The vessel and its tilting base (particularly the supporting ring, if provided) are structures whose deformations must be accepted according to experience in practice and according to the respective designs.

The levelling of the vessel in its tilting mount or cradle is effected, according to a known proposal, by moving the vessel on the undercarriage into its position under the converter tilting stand. In this position, in which the undercarriage must be secured against movement, the vessel is lifted from the undercarriage. Such lifting of the vessel is carried out to a level from which the vessel can be lowered later, with projections secured on the vessel wall coming into engagement with the respective future supporting surfaces in its mount. In general, there are used, for this purpose, claws which will bear later on the upper end surface of a horizontally arranged supporting ring. Usually, these claws are arranged opposite claws on the bottom end surface of the supporting ring, and which can be brought into force-transmitting contact with the supporting ring by the interposition of wedges, bars, etc.

Because of the thermal conductivity, that is, the property of the claws to move on the end surface of the supporting ring, abutments of complicated form are provided on the supporting ring for the claws. In a known arrangement, a supporting frame is rotatably mounted on the undercarriage, and the vessel claws are brought into a position opposite the abutments by rotation at the indicated level, and thus by turning the vessel about its vertical central axis. It can happen that the position of the undercarriage on the track is incorrect or unfavorable, because position deviations of the tracks must always be expected. The known arrangement then makes it necessary to repeat the entire starting movement, or at least to move the undercarriage sufficiently far until the supporting claws and the abutments oppose each other with sufficient accuracy. This procedure is particularly inexpedient, because the undercarriage must be supported on the floor in the lifted position of the vessel.

If the carriage must therefore be moved along the tracks, this means that any extended supporting means must be again retracted. This procedure becomes complicated when, as has been suggested, the undercarriage is supported on the floor, and is lifted, together with its driving gears and a supporting frame for the vessel. It may be advantageous, when the carriage changes direction at track intersections, to lift the entire unit, consisting of the undercarriage, the supporting frame and the vessel, and to turn the unit. Apart from the fact that this procedure requires considerable expenditure of energy, such an arrangement is not very expedient for minor corrections of the vessel position when it is threaded into its tilting support. The same thing can happen when, in a change of direction, a poor starting position exists for the placement of the undercarriage on the tracks extending in the new direction.

Another known proposal tries to avoid these disadvantages by mounting the hydraulic vessel-hoisting stands directly on the truck driving gears. However, this construction meets rather the requirement of permitting a position-correction in the direction of the track even when the supporting frame is lifted with the vessel. Such an arrangement again has the disadvantage that an additional device is required at the intersections of tracks during transportation of the vessel, and that, apart from the supporting frame for the vessel, four additional devices, for taking support against the floor, must be provided between each pair of hoisting means. Any assumed advantage during threading of the vessel is offset by the disadvantage occurring during crossing of track intersections.

SUMMARY OF THE INVENTION This invention relates to transportation lift trucks for hot vessels and, more particularly, to a novel transportation lift truck including improved means for hoisting a transported hot vessel, such as a steel-mill converter, into a supporting cradle or the like which is tiltable.

The present invention is based on the finding that an error exists when moving into the transfer position on the tracks, and that this error cannot be compensated or is deliberately not compensated. Such errors concem, for example, level inaccuracies which are due to the tolerances in the manufacture of the truck, or by the spring system of the truck, so that deviations from an exactly horizontal position exist. In general, such errors are also unavoidable in the tilting base or cradle. Depending on the construction of the tilting support or cradle, the local conditions of the tracks, and the properties of the transportation lift truck, the deviations either will cancel each other out or will augment each other.

The invention is directed to the problem of effecting threading of a supported hot vessel into its support despite these inaccuracies, not only for conventional steel-mill converter vessels provided with claw supports but also for special constructions, one of which is provided with the feature of a bolt-catch hole.

In accordance with the invention, this problem is solved by providing hoisting devices for a hot vessel on the undercarriage and preferably at two points which are opposite each other on the circumference of the vessel. These hoisting devices, which engage projections on the vessel, can be adapted automatically to the orientation assumed by the vessel during insertion of the vessel into the tilting support or cradle. The hoisting devices takeover the vessel in its position on the undercarriage. The principle of the invention sets in at a predetermined level in which the vessel has not yet reached its end position with sufficient accuracy but is already in contact with projections and the like on the tilting support.

The location of the fastening points in the tilting support determines the further lifting of the vessel into a terminal position in which all fastening points around the circumference of the vessel are in form-locking contact with the analogous fastening points in the tilting support. The particular advantage of the present invention resides in the automatic adaptation of the hoisting devices to given position deviations or orientation deviations of the vessel and its tilting support. Such an adaptation is particularly important from the standpoint of a damage-free assembly and disassembly of the vessel from its tilting support. The transportation lift truck embodying the invention solves both the difficulties during assembly of the vessel in its support and those during disassembly of a vessel from its support.

In a particularly advantageous embodiment of the invention, stirrups extend tangentially of the circumference of a vessel supported on the truck, and piston rod heads are gimbal-mounted on the upper ends of piston rods. Hydraulic piston drives are arranged in pairs on the undercarriage to extend the pistons. In general, two stirrups are sufficient to provide a stati cally determined system. However, in principle, it is also possible to provide stirrup-like or equivalent elements at three points of the vessel circumference. The gimbal-mounted heads of the piston rods permit the stirrups to assume a considerable angular deviation from a horizontal plane.

It is preferable to let the stirrups act in dependence on the type of the fastening elements on the vessel circumference, as well as on the form of the vessel wall in the central and bottom regions of the vessel. In accordance with another feature of the invention, the piston rod heads, provided with Cardan joints, are connected by means of substantially vertical tie rods to the stirrups, and the latter can be engaged tangentially under a reinforcing ring rigidly connected with the vessel. This measure serves to provide for the application of force by the stirrups in the lower region of the vessel. It is a particular advantage to compensate these inaccuracies appearing in practice by providing Cardan joints on the stirrup supporting ends of the tie rods also.

The transportation lift truck embodying the invention has the advantage that the piston rod heads, serving as Cardan joints, are provided with two double pins extending perpendicularly to each other, a pair of tie rods acting on a double pin, and with each pin of a double pin forming, in turn, itself a Cardan joint with a tie rod end. This design assures the independent movement of the tie rods as soon as they are forced from a vertical orientation by a displacement of a stirrup. It should be noted that such stirrup deviations can take place in three planes which are perpendicular to each other.

In accordance with another feature of the invention, the stirrups have forked ends and both arms of each fork serve to suspend the associated stirrup on a pin of a Cardan joint. It is advantageous to provide a symmetrical arrangement of the Cardan joint pins at both sides of the housing or cylinder of a piston drive, or of a similar lifting column. This arrangement also permits moving the piston drive very close to the center of the undercarriage, thus enabling the attainment of a very narrow undercarriage.

Another advantage of the invention resides in the fact that a special Cardan joint body, for the hinge pins, is provided on the piston rod head, and with the forks, at the end of the stirrups, serving as pivot bearings. This corresponds favorably to the given prerequisites insofar as the piston rod extends centrally from its cylinder housing, so that the connecting point of the piston rod head can be designed as a bearing block. A symmetrical application of force, and thus a balanced loading of the hoisting pistons, is assured by the forked design at the ends of each stirrup.

For mounting purposes, and in order to enhance the mobility of the arrangement, it is further advantageous that the tie rod ends are provided with cross-pins and suspended, at least on the piston rod head end, in recesses of the Cardan joint body.

An object of the invention is to provide an improved transportation lift truck for hot vessels.

Another object of the invention is to provide such a truck including vessel hoisting means adapting to the orientation assumed by a vessel during insertion of the vessel into a tilting support.

A further object of the invention is to provide such a transportation lift truck which is free of the disadvantages of prior art arrangements.

Another object of the invention is to provide such a transportation lift truck which is relatively simple in construction and economical to manufacture.

For an understanding of the principles of the invention, reference is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a side elevation view of a transportation lift truck embodying the invention, with a transported vessel being indicated, in transporting position, in broken lines;

FIG. 2, is a symmetrical one-half of a top plan view corresponding to FIG. 1;

FIG. 3 is an end elevation view of the truck with a supported vessel being shown, in broken lines, in its terminal or operating position wherein it is fully engaged in a tilting support; and

FIG. 4 is a partial cross-sectional view through a lower portion of the undercarriage.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a transportation and lift truck 1 comprises substantially an undercarriage 2, driving gearing 3 and 4 and wheels 5 and 6, driven by the driving gearing and running on tracks 7 and 8. The driving gearings 3 and 4 preferably are designed as double pivoted link drives, and are supported between the pivoted links 9 and 10 by means of spring packs 11. At opposite ends of its lower region, undercarriage 2 is provided with drivers cabs 12 and 13 and, in the center between the driving gearings 3 and 4, there is provided an arrangement of hydraulic piston-cylinder actuators 14 and 15, as best seen in FIG. 2. It is advantageous if all four hydraulic actuators are combined in a common housing 16 as, with such an arrangement, there is formed a housing which can be adapted to the correspondingly high hydraulic pressures and which can be easily protected against environmental influences.

The subject matter proper of the invention is arranged on undercarriage 2 and, for this purpose, undercarriage 2 has a large central recess 17 to provide room for the bottom of a converter vessel 19. Undercarriage 2 thus forms substantially a base bounding the outer form of the vehicle. Nevertheless, there is sufficient room for the bottom part 18 of converter vessel 19 between hydraulic actuators 14 and 15.

At the four corners of undercarriage 2 there are arranged hydraulic hoisting arrangements 21 and, in the illustrated embodiment, these are hydraulic pistoncylinder actuators cooperating in pairs. The piston rods 23, whose extended position can be seen only in FIG. 3 at the right, carry respective bearing blocks 24. Each bearing block 24 rotatably supports a pin 25 which can be seen particularly at the left in FIG. 2. Each hinge pin 25, which is designed as a double pin, is retained in a Cardan joint body 26, which is formed to receive a second pair of hinge pins 27, 27. To this end, Cardan joint body 26 forms, through an outer part 28, an additional pivot bearing 29. Hinge pins 27 form connecting points 30 (FIGS. 1 and 2) for the upper ends of tie rods 31.

On the lower or opposite ends of tie rods 31, relative to connecting points 30, there are provided somewhat similarly designed connecting points 32 for stirrups 33 which, in the illustrated embodiment, are arranged at the opposite ends 34 and 35 of undercarriage 2. These stirrups cooperate with vessel 19 through projections on the exterior surface of the vessel and, in the illustrated embodiment, such abutments for vessel 19 are provided on its circumference 36 in the form of circle segments 37. The vessel projection, which is thus utilized, comprises a reinforcing ring 38 which has two, or three, or even more catch holes 39 distributed around its circumference and which cooperate with respective catch bolts 40 which, in turn, are secured on a supporting ring proper forming part of the tilting support which has not been illustrated as it forms no part of the invention. Only pivot pins 42 and 43 of the tilting support are indicated in FIG. 3.

When the piston drives 22 are actuated, which is generally effected in synchronism, the piston rods 23 of all of the piston drives extend and lift stirrups 33 up to the level designated in broken lines at 44 in FIG. 3. During this procedure, catch bolts 40 have engaged in the catch-bolt holes 39, with any resistance being overcome by the Cardanic suspension of stirrups 33. The position of vessel 19 shown in FIG. 3 is therefore the operating position in its support. In this position, the force-locking connection of the vessel to its support can be readily closed, depending on the suspension of the vessel, so that the lift truck has performed its function. Inclined positions of supporting ring 41, as represented in FIG. 1, are acceptable and, in general, they even exceed an angle of 20 to the horizontal. In practice, such angles will rarely be utilized, but it has been found that the invention is capable of overcoming such angles when inserting the vessel into its support. This property is particularly advantageous with greatly distorted parts of the tilting support.

Additional advantages of the hoisting devices 21 will now be described. The hydraulic piston drives 22 have large diameter housings or cylinders 45, and the piston drives 22 extend, additionally and in order to accommodate the relatively long piston rod and its guide element, respectively, downwardly of undercarriage 2 through the medium of reduced diameter piston rod extensions 46.

Bearing blocks 24, serving as piston rod heads, have respective Cardan joints 47 of a certain type, while the connecting parts 32 of tie rods 31 on stirrups 33 have respective Cardan joints 48 of a somewhat different joint. Both Cardan joints 47 and 48, however, include identical tie rod ends 49. As best seen at the left in FIG. 1, each upper tie rod end 49 includes a hinge pin 27 as a separate pin which need not necessarily serve as a part of the joint body 26. Instead, in the illustrated embodiment, there are provided recesses 50 in the joint body 26 and its outer part 28, with each pair of recesses receiving a hinge pin 27. In addition, a respective joint body 51 is arranged on each upper tie rod end 49 to receive hinge pins 27, as best seen at the left in FIG. 2, and which is further designed to receive two pins 52 and 53 extending transversely and perpendicularly to the associated hinge pin 27. Thus, each upper tie rod end 49 can be turned both about the axis of hinge pin 27 and about the common axis of pins 52 and 53, to form a separate Cardan joint 54.

The respective ends 55 and 56 of each stirrup 33 are formed as forks 57, which can be clearly seen in the plan view of FIG. 2. Each of the fork arms or tines 58 and 59 engages a pivot pin 60 forming part of a lower tie rod end 49 and corresponding substantially to a pin 27. As best seen in FIG. 3, the tines are formed with downwardly directed recesses 61 engaging pivot pins 60 and corresponding substantially to the aforementioned recesses 50. Cardan joint 48 therefore is suspended similarly to Cardan joint 47, with the respective recesses 61 and 50 extending in opposite directions with respect to the supporting forces.

FIG. 4 illustrates details in the lower region of the undercarriage 2, and it can be seen clearly how the vessel bottom 62 comes to lie in a depression of the frame part 63. This figure also illustrates how hydraulic pistons 14 and 15 are mounted in their housing 16. It can further be seen that pistons 14 and 15 need only have relatively short lifting strokes and assure, with particular advantage, a large supporting surface despite their relatively narrow construction.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. In a transportation lift truck, for hot vessels having an external projection for support of the vessel, particularly steel-mill converters adapted to be supported in a tilting support, and including an undercarriage having driving means for moving the truck along tracks and carrying hydraulic actuator means operable to lift the undercarriage at track intersections to change the direction of movement of the truck along the tracks: the improvement comprising, in combination, hoisting means on said undercarriage engageable with vessel projections at at least two points of the vessel periphery, and operable to lift a vessel from said undercarriage into a tilting support for securement in the latter; and means included in said hoisting means accomodating adaption of the entire vessel to the orientation assumed by the entire vessel during insertion thereof into a tilting support.

2. In a transportation lift truck, the improvement claimed in claim I, in which said hoisting means comprises hydraulic piston-cylinder actuators arranged in pairs on said undercarriage and each including an upwardly extensible piston rod having a respective head gimbal-mounted at its upper end; and stirrups each supported from a pair of piston rod heads and oriented to extend tangentially of the circumference of a vessel carried by said truck.

3. In a transportation lift truck, for hot vessels having an external projection for support of the vessel, particularly steel-mill converters adapted to be supported in a tilting support, and including an undercarriage having driving means for moving the truck along tracks and carrying hydraulic actuator means operable to lift latterand means adapting said hoisting means to the orientation assumed by a vessel during insertion thereof into a tilting support; said hoisting means comprising hydraulic piston-cylinder actuators arranged in I pairs on said undercarriage and each including an upwardly extensible piston rod having a respective head gimbal-mounted at its upper end; stirrups each supported from a pair of piston rod heads and oriented to extend tangentially of the circumference of a vessel carried by said truck; Cardan joints on each piston rod head; and substantially vertically oriented tie rods connected to said joints and to said stirrups; said stirrups being arranged to extend tangentially under a reinforcing ring fixedly connected with a vessel positioned on said truck.

4. In a transportation lift truck, the improvement claimed in claim 3, in which the connecting points of said tie rods to said stirrups comprise further Cardan joints.

5. In a transportation lift truck, the improvement claimed in claim 3, in which each piston rod head supports two double pins extending perpendicularly to each other; each set of two double pins supporting a pair of tie rods; each end of one double pin forming, with the associated tie rod end, a Cardan joint.

6. In a transportation lift truck, the improvement claimed in claim 4, in which the opposite ends of said stirrups are forked to provide two spaced fork tines; each fork tine engaging a respective pivot pin of the associated one of said further Cardan joints.

7. In a transportation lift truck, the improvement claimed in claim 5, in which each of said double pins is engaged in a Cardan joint body mounted on the associated piston rod head through the medium of one of said two double pins.

8. In a transportation lift truck, the improvement claimed in claim 7, in which said stirrups are forked at their opposite ends to provide spaced fork tines; each fork tine being engaged with a respective pin of a further Cardan joint at the lower end of the associated tie rod; said forks being designed as pivot bearings for the associated stirrup.

9. In a transportation lift truck, the improvement claimed in claim 8, in which the upper tie rod ends carry cross-pins engaged in upwardly opening recesses of the Cardan joint body.

10. In a transportation lift truck, the improvement claimed in claim 9, in which the lower tie rod ends have cross-pins engaged in downwardly opening recesses in said forks. 

1. In a transportation lift truck, for hot vessels having an external projection for support of the vessel, particularly steel-mill converters adapted to be supported in a tilting support, and including an undercarriage having driving means for moving the truck along tracks and carrying hydraulic actuator means opeRable to lift the undercarriage at track intersections to change the direction of movement of the truck along the tracks: the improvement comprising, in combination, hoisting means on said undercarriage engageable with vessel projections at at least two points of the vessel periphery, and operable to lift a vessel from said undercarriage into a tilting support for securement in the latter; and means included in said hoisting means accomodating adaption of the entire vessel to the orientation assumed by the entire vessel during insertion thereof into a tilting support.
 2. In a transportation lift truck, the improvement claimed in claim 1, in which said hoisting means comprises hydraulic piston-cylinder actuators arranged in pairs on said undercarriage and each including an upwardly extensible piston rod having a respective head gimbal-mounted at its upper end; and stirrups each supported from a pair of piston rod heads and oriented to extend tangentially of the circumference of a vessel carried by said truck.
 3. In a transportation lift truck, for hot vessels having an external projection for support of the vessel, particularly steel-mill converters adapted to be supported in a tilting support, and including an undercarriage having driving means for moving the truck along tracks and carrying hydraulic actuator means operable to lift the undercarriage at track intersections to change the direction of movement of the truck along the tracks: the improvement comprising, in combination, hoisting means on said undercarriage engageable with vessel projections at at least two points of the vessel periphery, and operable to lift a vessel from said undercarriage into a tilting support for securement in the latter; and means adapting said hoisting means to the orientation assumed by a vessel during insertion thereof into a tilting support; said hoisting means comprising hydraulic piston-cylinder actuators arranged in pairs on said undercarriage and each including an upwardly extensible piston rod having a respective head gimbal-mounted at its upper end; stirrups each supported from a pair of piston rod heads and oriented to extend tangentially of the circumference of a vessel carried by said truck; Cardan joints on each piston rod head; and substantially vertically oriented tie rods connected to said joints and to said stirrups; said stirrups being arranged to extend tangentially under a reinforcing ring fixedly connected with a vessel positioned on said truck.
 4. In a transportation lift truck, the improvement claimed in claim 3, in which the connecting points of said tie rods to said stirrups comprise further Cardan joints.
 5. In a transportation lift truck, the improvement claimed in claim 3, in which each piston rod head supports two double pins extending perpendicularly to each other; each set of two double pins supporting a pair of tie rods; each end of one double pin forming, with the associated tie rod end, a Cardan joint.
 6. In a transportation lift truck, the improvement claimed in claim 4, in which the opposite ends of said stirrups are forked to provide two spaced fork tines; each fork tine engaging a respective pivot pin of the associated one of said further Cardan joints.
 7. In a transportation lift truck, the improvement claimed in claim 5, in which each of said double pins is engaged in a Cardan joint body mounted on the associated piston rod head through the medium of one of said two double pins.
 8. In a transportation lift truck, the improvement claimed in claim 7, in which said stirrups are forked at their opposite ends to provide spaced fork tines; each fork tine being engaged with a respective pin of a further Cardan joint at the lower end of the associated tie rod; said forks being designed as pivot bearings for the associated stirrup.
 9. In a transportation lift truck, the improvement claimed in claim 8, in which the upper tie rod ends carry cross-pins engaged in upwardly opening recesses of the Cardan joint body.
 10. In a Transportation lift truck, the improvement claimed in claim 9, in which the lower tie rod ends have cross-pins engaged in downwardly opening recesses in said forks. 